EinST

No, it shouldn't be 5V. I wasn't making it up when I said that the PCM supplies ignition voltage (battery voltage, switched on with key on) on each circuit. Of course, I'm basing this on the 4T40-E transaxle in general and not your particular vehicle. Perhaps you should consider an online subscription to alldatadiy.com or eautorepair.net.

luvchevys

used the modis scantool to read the trans sensors the range sensor and tpf sensor all read hi low as they should according to the flow chart if everything is reading as it should and the trans shifts fine on first trip cycles what could possibly be causing the p1810 and p1815 codes i have checked the wiring and the outputs and replaced the range sensor and tpf sensor and pressure regulator

EinST

On the 2003 Cavalier, there's TSB #03-07-30-021A that says the date code on the new TFP switch should be 2308 or higher (see TSB_03-07-30-021A.pdf). If not that, the failure may be happening at a certain fluid temperature.

luvchevys

the code sets by simply starting the car shutting it off and restarting it it does not have to be shifted or driven or warmed up if the codes set because of mismatched logic and the scantool is showing them to be correct and matching and the code sets without even shifting the vehicle what else could the problem be

EinST

Without moving the shifter? There's just a couple of failure scenarios in that case:

1. Illegal TFP switch state 111 or 101
2. Gear range not in Park or Neutral during engine startup

Since you say you verified everything with a scan tool, I'm out of ideas. Perhaps consider a visit to a transmission shop.